1. Field of the Invention
The present invention relates to a recycle document feeder which is mounted on an image forming apparatus such as a copying machine, a facsimile machine, an image reader or the like, and adapted to feed a document original to be read by the image forming apparatus from a document placing plate to a reading position and then back onto the document placing plate after image reading of the document original.
2. Description of Related Art
Recycle document feeders are conventionally known which are mounted on a copying machine, for example, and adapted to automatically feed a document original previously set on a document placing plate onto a contact glass of the copying machine and then back onto the document placing plate after image reading of the document original.
The recycle document feeders typically include a pair of document width regulating guides for positioning the document originals to be fed with respect to a direction perpendicular to a document transportation direction. The pair of document width regulating guides are slid so that a spacing therebetween is adjusted to conform to the width of the document originals, and then the document originals are placed on the document placing plate. Thus, the document originals are positioned with respect to the direction perpendicular to the document transportation direction.
Some of the recycle document feeders are adapted to slightly reciprocate the pair of document width regulating guides perpendicularly to the document transportation direction (or in a direction in which the document width regulating guides are slid) to align the document originals fed back onto the document placing plate with respect to the direction perpendicular to the document transportation direction. The slight reciprocation occurs every time a document original is fed back. Thus, the document originals fed back onto the document placing plate can smoothly be transported to a predetermined setting position for re-feeding thereof.
During the document transportation operation, however, the slight reciprocation of the document width regulating guides in the prior art document feeder causes an operation noise, which may grate upon user's ears.
In addition, the provision of a mechanism for slight reciprocation of the document width regulating guides complicates the construction of the document feeder, thereby increasing the costs of the feeder.